Cutaneous fungi Flashcards
two types of cutaneous fungi
- Dermatophytoses
- Dermatomycoses
“Plants on the skin”
Dermatophytoses
Infection involves the skin, hair and nails
Dermatophytoses
Fungal diseases caused by a group of fungal organisms other thandermatophytes
Dermatomycoses
Infections involve only the skin
Dermatomycoses
Three classifications of dermatophytes
Epidermophyton
Microsporum
Trichophyton
attacks skin and nails
Epidermophyton
attacks Hair, skin
Microsporum
attacks hair, skin, and nails
Trichophyton
fungus that invades the keratinized portions of the hair, skin, hair and nails
*keratin as a nitrogen source
Dermatophytes
has no microconidia
Epidermophyton
has few microconidia
Microsporum
has many microconidia
Trichophyton
macroconidia: Smooth, thin walls; sparse in number
Epidermophyton
macroconidia: Thick, rough walls; many present
Microsporum
macroconidia: Smooth thin walls; relatively few present
Trichophyton
CLASSIFICATION OF DERMATOPHYTES BY ORIGIN
anthrophilic (people)
geophilic (soil)
zoophilic (animals)
few conidia in culture
anthrophilic
most number of conidia in culture
geophilic
moderate number of conidia in culture
zoophilic
Anthropophilic/ Zoophilic/Geophilic
Microsporum gypseum
Geophilic
Anthropophilic/ Zoophilic/Geophilic
Microsporum canis
Zoophilic
Anthropophilic/ Zoophilic/Geophilic
Trichophyton vanbreuseghenii
Geophilic
Anthropophilic/ Zoophilic/Geophilic
T. mentagrophytes complex (granular isolates)
Zoophilic
Anthropophilic/ Zoophilic/Geophilic
Trichophyton verrucosum
Zoophilic
Dermatophytoses are generally called
tineas (L: ringworm)
8 dermatophytosis
Tinea corporis
Tinea cruris
Tinea pedis
Tinea manuum
Tinea barbae
Tinea unguium
TInea capitis
Tinea imbricata
Dermatophytosis of the body or trunk plus neck and shoulder
Tinea corporis
lesions of tinea corporis
Erythematous circular lesions
scaly patch with sharply demarcated margins
transmission of tinea corporis
direct contact, fomite, autoinoculation
causative agent of tinea corporis
Trichophyton rubrum
Trichophyton mentagrophytes
T. tonsurans
M. canis
Dermatophytosis of the proximal medial thighs, perineum, and buttocks.
Tinea cruris
other term of tinia cruris
jock itch
scaly, erythematous to tawny brown, bilateral and asymmetric lesions
sharply marginated border
frequently studded with small vesicles.
lesions of tinia cruris
causative agents of tinea cruris
T. rubrum
T. mentagrophytes
E. floccosum
Dermatophytosis of the feet
Tinea pedis
other term for tinea pedis
“athlete’s foot”
maceration, peeling, pruritic, and painful fissuring between the
fourth and fifth toes,
tinea pedis lesion
hyperkeratotic chronic infection of the sole
“moccasin foot”
causative agent of tinea pedis
T. rubrum (chronic)
E. floccosum (acute)
T. mentagrophytes var. interdigitale
Dermatophyte infections on the palms and between fingers.
Tinea manuum
causative agent of Tinea manuum
M. canis
T. mentagrophytes var interdigitale
T. rubrum
T. tonsurans
Occurs only on the bearded areas of the face and neck.
Tinea barbae
Superficial form of tinea barbae
resemble tinea corporis
Pustular form of tinea barbae
associated with zoophilic dermatophytes
May develop to alopecia and permanent scarring
Tinea barbae
causative agents of tinea barbae
T. verrucosum
T. mentagrophytes
T. schoenleinii
Dermatophytosis of the nails
Tinea unguium
whitish patches on the surface of the nail contain fungus but
the nail is not distorted
Superficial
tinea unguium where deep layers of the skin is invaded and nail becomes brittle and thickened and is frequently discolored
Subungual form
causative agent of tinea unguium
T. rubrum (proximal subungual)
T. interdigitale (nodular variant of T. mentagrophytes)
T. schoenleinii
T. violaceum
E. floccosum
Dermatophytosis of the hair of the scalp, eyebrows, and eyelashes
Tinea capitis
Causative agent of Tinea capitis
T. tonsurans
M. canis
specialized form of tinea corporis
Tinea imbricata
lesions are ringlike growth in overlapping circles
Tinea imbricata
causative agent of T. imbricata
T. concentricum
CATEGORIES OF HAIR INFECTION
Endothrix
Ectothrix
Favic type
infects the inner portion of the hair
Endothrix
arthroconidia appear as tile mosaic sheath around the hair
ectothrix
hair becomes grayish, dull, discolored, becomes brittle and breaks off
ectothrix
fluoresce green under wood’s lamp
ectothrix
chain of arthroconidia inside shortened hair stubs
endothrix
hair lose luster, becomes brittle and breaks off above surface of the shaft
endothrix
conidia in the shafts of the hair stubs appear black dots leaving graying patch
endothrix
wood’s lamp negative
endothrix
Creates parallel lesions with the hair shaft.
Faic
Hair shaft is filled with long filamentous arthroconidia; empty air-
filled areas are left in the hair when they hyphae degenerate into fat
droplets.
favic
odor or favic lesions
mousy
epithelial debris which forms yellowish, cup-shaped crusts in favic
scutula
dull green in wood’s lamp
favic
Ectothrix agents
M. audouinii
M. canis
M. ferrugineum
M. gypseum (Nannizzia gypsea) complex
M. (Nannizzia) praecox
T. megninii
T. mentagrophytes complex
T. verrucosum
endothrix agents
T. soudanense
T. tonsurans
T. violaceum
favic agents
T. schoënleinii
Flat to velvety, thin, pale salmon to pale brownish reverse.
Microsporum audouinii
Flat to velvety, thin, pale to yellow, with yellow (rarely pale) reverse
Microsporum canis var. canis,
Granular, sandy in color, or occasionally light cinnamon or rosy buff., Reverse usually pale to brownish
Microsporum gypseum complex
Granular to powdery, yellow-cream to buff surface, Pale to red brown reverse.
Trichophyton mentagrophytes,
Powdery to low velvety, cream to deep red, Typically wine red reverse but yellow variants occasional; red color
poorly formed in presence of common bacterial contamination
Trichophyton rubrum,
Convoluted with glabrous texture, heaped or folded topography.
Slightly velvety whitish colony.
Trichophyton schoenleinii,
Surface is brownish yellow to olive gray or khaki with a suede like
surface, raised and folded in the center, with a flat periphery and
submerged fringe of growth.
Epidermophyton floccosum
Classification of M. canis
zoophilic
growth pattern of M. canis
rapid
Classification of M. gypseum
geophilic
Growth pattern of M. gypseum
rapid growth
Type 1 T. mentagrophytes
var mentagrphytes
classification of type 1 T. mentagrophytes
zoophilic
growth pattern of T. mentagrophytes
intermediate
type 2 T. mentagrophytes
var interdigitale
Type 2 T. mentgrophytes classification
anthropophilic
T. rubrum classification
anthropophilic
T. rubrum growth
slow growth
T. tonsurans classification
anthropophilic
T. tonsurans
intermediate to slow growth
T. concentricum classification
anthropophilic
T. concentricum growth
slow growth
T. verrucosum classification
zoophilic
T. verrucosum growth
slow, improved at 37 C
T. schoenleinii classification
anthropophilic
T. schoenleinii growth
slow growth
T. violaceum classification
anthropophilic
T. violaceum growth
slow growth
E. floccosum classification
anthropophilic
E. floccosum growth
intermediate
Polished rice test
M. canis (+)
M. audouinii (-)
Incubation of polished rice test
6-10 days
25- 30 C
Hair perforation test positive
T. mentagrophytes
T. tonsurans
T. violaceum
M. canis
M. gypseum
Hair perforation test negative
T. rubrum
incubation of hair perforation test
4 weeks t RT
culture medium of urease test
christensen’s agar
Stuart’s broth
urease positive test result and interpretation
red to purple in less than 4 day
T. mentagrophytes
urease negative test result and interpretation
no color change T. rubrum
growth factor test medium
casamino acid agar/ trichophyton agar
components of trichophyton agar
Nicotinic acid
L-histidine
growth factors
growth factors in growth factor test
thiamine
inositol
results in growth factor test
T. verrucosum = growth in inositol
T. violaceum = growth in inositol and thiamine
Pigmentation:
Obverse: White that tends to turn khaki green-brown, center is folded
Reverse: Yellow-brown with observable folds
E. floccosum
Flat, slightly granular at first
E. floccosum
“Snowshoes”, “paddles”, or “beaver’s tail” macroconidia
E. floccosum
Pigmentation:
Obverse & reverse: Initially cream then becoming lavender or purple
T. violaceous
Verrucose and glabrous
T. violaceum
Absent conidia
Swollen hyphae containing cytoplasmic granules
T. violaceum
Pigmentation:
Obverse: white to tan
Reverse: colorless or light yellow
T. schoenleinii
Convoluted to folded and glabrous to slightly velvety
Often submerged into the surrounding medium
T. schoenleinii
“Mousy” odor typically develops in cultures
T. schoenleinii
No conidia produced
Hyphae:
Hyaline and septate
“Favic chandeliers”, “antlers”, or
“nailhead”
T. schoenleinii
Pigmentation:
Obverse: white or cream
Reverse: colorless or salmon
T. verrucosum
Commonly small
Convoluted with raised center and flat periphery
Submerged growth
Glabrous to slightly velvety
T. verricosum
Macroconidia are rare, 3-5 cells, thin-walled,
“RAT-TAIL”
Microconidia are large, clavate, and lateral
T. verricosum
Pigmentation:
Obverse: white that becomes honey-brown
Reverse: yellow
T. comcentricum
Folded and furrowed
T. concentricum
Macroconidia and microconidia are rare
Masses of tangled hyphae, presence of
chlamydospores
T. comcentricum
Pigmentation:
Obverse: yellow
Reverse: yellow-brown to chestnut-red-brown
T. tonsurans
Flat and velvety to powdery
T. tonsurum
Macroconidia are absent or rare, distorted
Many microconidia of various size and shapes
with flattened base
“Balloon forms” – aged pleomorphic microconidia
T. tonsurans
Pigmentation:
Obverse: cream to deep red
Reverse: wine-red
T. rubrum type 2
Powdery to low velvety
T. rubrum type 2
Microconidia are tear-shaped, single, and lateral along the hyphae
Abundant wine-red, water-soluble pigment
T. rubrum
Pigmentation:
Obverse: White to reddish
Reverse: Wine-red (occasionally yellow)
T. rubrum type 1
Cottony to velvety
T. rubrum type 1
Macroconidia are few, smooth-walled, pencil- shaped, attached directly to the hyphae
T. rubrum
Which T rubrum type has more conidia
type 2
Pigmentation:
Obverse: cinnamon-colored
Reverse: light tan
M. gypseum
Flat and granular
M. gypseum
Macroconidia: 3-9 celled, broadly spindle- shaped, rough-walled; Terminal ends may be rounded
Microconidia: If present, single or in small clusters
M. gypseum
Pigmentation:
Obverse: White to buff
Reverse: Yellow (rarely pale)
M. canis
Cottony to granular
M. canis
Macroconidia: 6-15 cells; Assymetrical beak apex; Abundant, spindle-shaped with thick, rough walls
M. canis
Microconidia: Clavate or pyriform, laterally attached to hyphae
M. canis
Hyphae: Hyaline, septate, branching
M. canis
Hyphae: Hyaline, septate, branching
M. audouinii
Flat and velvety
M. audouinii
Conidia: Absent, bizarre if present
M. audouinii
Atypical vegetative pectinate hyphae with terminal chlamydospores
M. audouinii
Macroconidia: uncommon, cigar-or pencil-shaped with thin, smooth walls, 3-6 cells
T. mentagrophytes
Microconidia: Unicellular, arranged singly along the hyphae on short pedicles or “en grappe”
T. mentagrophytes var mentagrophytes
Clavate or pyriform-shaped arranged singly in sleeves en thryses along the hyphae by pedicles
T. mentagrophytes var interdigitales
Hyphae: Hyaline, septate, and branched; spiral
form in 30% of isolates
T. mentagrophytes
Specimens for lab dignosis of cutaneous fungi
Skin scrapings
Hair
Nail clippings
hair mycoses with arthroconidia
endothrix and actothrix
hair mycoses without arthroconidia
favic type
two methods for direct microscopy
KOH
calcofluor white
incubation of SDA
25-30 C 1-3 weeks
antimicrobial agents in mycosel or mycohiotic agar
chloramphenicol - bacteria
cycloheximide - saprobes
selective for dermatophytes in DTM
cycloheximide
chlortetracycline
gentamicin
differential for dermatophytes
phenol red, red for presence of dermatophytes
Hypersensitivity reaction to dermatophytic infection elsewhere in the body
Dermatophytid reaction
Yellowish, circular lesions with a characteristic “mousy” odor
scutula
“BLACK DOT” Tinea capitis
endothrix
“GRAY-PATCH” Tinea capitis
ectothrix
Causative agent of favic type
T. schoenleinii
causative agents of endothrix
Trichophyton tonsurans
Trichophyton violaceum
Causative agents of ectothrix
Trichophyton mentagrophytes
Trichophyton verrucosum
Microsporum audouinii
